The Impact Of Hypertension On The Pulmonary Vein Physiological Characteristics

Objective: To explore the possible role of pulmonary vein in the mechanism ofhypertension related atrial fibrillation by studying the impact of hypertension onpulmonary vein and atrial electrophysiological characteristics and susceptibility to atrialfibrillation.Methods:32patients from our hospital (2012.1-2012.7) received radiofrequencyablation and diagnosed with left accessory pathway (AP) by electrophysiological testwere enrolled in this study. Divided them into two groups depending on whether theyhave the diagnosis of hypertension. Hypertension group:15cases diagnosed with leftAP with hypertension. Control group:17patients diagnosed with left AP withouthypertension. All patients received atrial septal puncture and ablation catheter was sentinto the left atrium. Before ablation, we measured the relative refractory period andthe effective refractory period of the atrium and pulmonary vein antrum respectively in8parts of the upper right, lower right, upper left, lower left pulmonary venous vestibule,proximal end of coronary sinus and the distal end of coronary sinus, high right atrium,low right atrium with stimulate of0.1ms pulse width,2times diastolic threshold, S1S2starting from500/400ms,-5ms steps.Also we calculated refractory period dispersion,atrial conduction time, atrial susceptibility window, atrial vulnerable period respectively.The relative refractory period is defined as the the S2interval in which there is5msprolongation of atrial conduction time while step length shorten5ms. Atrial conductiontime is defined as the period while stimulation conducted from high right atrium to thedistal end of the coronary sinus. Refractory period dispersion is defined as thedispersion of effective refractory period in each position respectively. Atrial vulnerableperiod is defined as the difference between relative refractory period and the effectiverefractory period in each part respectively. And we also recorded the occurrence of atrialarrhythmias (induced atrial echo and atrial fibrillation were recorded), calculated the atrial susceptible window, namely the longest S2interval that inducing atrialarrhythmia.Results:1.The effective refractory period of pulmonary venous vestibule and eachposition of the atrium were compared in two groups, hypertension group first: theproximal coronary sinus effective refractory period (211.15±18.83) and (223.57±24.59) ms, P=0.05; the distal end of the coronary sinus effective refractory period were(218.21±19.79) and (236.15±20.53) ms, P=0.02; high right atrial effective refractoryperiod (227.5±15.09) and (227.8±14.51) ms, P=0.2; low right atrial effectiverefractory period were (213.08±18.24) and (210±29.67) ms, P=0.32; right superiorpulmonary vein effective refractory period (235±18.89) and (241.25±22.08) ms, P=0.11; right lower pulmonary vein effective refractory period were (221.67±17.67) and(245±46.69) ms, P=0.02; effective refractory period of the left superior pulmonaryvein (232.33±24.55) and (249.12±41.55) ms, P=0.04; left inferior pulmonary veineffective refractory period (224.33±14.59) and (239.12±29.73) ms, P=0.03.2.The vulnerable period of pulmonary venous vestibule and each position of the atriumwere compared, hypertension group first: the proximal end of coronary sinus vulnerableperiod (46.79±12.34) and (45.38±36.35) ms, P=0.45; the distal end of coronarysinus vulnerable period were (43.46±14.59) and (37.69±29.97) ms, P=0.27; highright atrial vulnerable period (47.5±19.34) and (47.18±27.89) ms, P=0.48; low rightatrial vulnerable period were (65.33±20.85) and (39±19.73) ms, P=0.0007; rightsuperior pulmonary vein vulnerable period were (38.21±12.62) and (32.67±14.69) ms,P=0.21; the right inferior pulmonary vein vulnerable period were (48.85±12.88) and(31.67±10.88) ms, P=0.0004; the left superior pulmonary vein vulnerable period were(38.67±12.04) and (35.33±26.22) ms, P=0.33; left inferior pulmonary veinvulnerable period were(56.07±16.28) and (37.31±17.77) ms, P=0.0043.The effective refractory period dispersion of pulmonary vein and atrial in thehypertension group were larger than the control group4.The impact of hypertension on the vulnerable period of the pulmonary vein is moreobvious than the vulnerable period of atrial. We calculate the difference of averagevulnerable period between the hypertension group and the control group: the fourpulmonary veins were44.82ms and the four parts of the atrium were33.84ms.5.Atrial conduction time: the average time were55.4ms in the hypertension group, and43.5ms in the control group. 6.Between the two groups, there is no significant difference of the atrial effectiverefractory period between the two groups (hypertension group20.03, control group18.53, P>0.05), but there is statistical signification (hypertension group, the controlgroup19.0520.32, P <0.05) when combining atrial and pulmonary vein refractoryperiod dispersion in entirety.Conclusion:1.The refractory period of pulmonary veins and atrium are short andthe refractory period dispersion are large in hypertension patients.2.The vulnerableperiod of pulmonary veins and atrium are long and the susceptibility to atrial fibrillationare increased in hypertension patients.3.The impact of hypertension on thephysiological characteristics of the pulmonary vein is more obvious compared with theimpact on atrium, prompting pulmonary may play an important role in in themechanism of hypertension related AF.